The use of optical indicia, such as bar code symbols, for product and article identification is well known in the art. Presently, various types of indicia reading terminals have been developed, such as hand-held bar code scanners, hands-free scanners, bi-optic in-counter scanners, and mobile computers such as personal digital assistants (PDAs).
One common type of indicia reading terminal is the digital imager, which includes 1D (linear) imagers and 2D (area) imagers. Variable focus digital imagers typically utilize a lens to focus the image of the bar code onto a multiple pixel image sensor, to capture an image for recognition and decoding purposes. Resolution of the image sensor is one of the key parameters defining the depth of field of the indicia reading terminal.